1. Field of the Invention
The present invention relates to valves and more particularly, to a toggle gate valve that is also suitable for high pressure, high temperature applications and which provides a double block and bleed configuration.
2. Prior Art
Various gate valves that utilize toggle linkages to effect valve opening and closing have been disclosed in the prior art. By way of example, U.S. Pat. No. 1,707,125 to Loffler discloses a gate valve having a toggle linkage connecting a seal plate to an actuator plate. Similarly, U.S. Pat. No. 2,850,260 to Perazone et al discloses a valve having a toggle linkage for forcing the seal plate into a tight closed position. Unfortunately, none of the prior art toggle gate valves known to the applicants comprises a double block and bleed configuration in which the cavity between the seal rings and the sealing surface can be bled to improve the integrity of the seal or can be injected with grease. Furthermore, toggle gate valves are inherently complex and tend therefore to be difficult and costly to manufacture as well as time consuming and costly to service.